In this work we report the NOx removal by reduction using two types of plasma reactors; the plasma-driven catalyst (PDC) reactor and the plasma-enhanced selective catalytic reduction (PE-SCR) reactor. In the PDC system, reduction was found to be the dominant pathway of NOx removal under the presence of additives. Gas hourly space velocity (GHSV) and type of additives were found to be important parameters which determine the removal rates of NO and NOx in the PDC system. In the PE-SCR system with NH3, the plasma converted most of NO to NO2, and total NOx was successfully reduced over the Co-ZSM5 catalyst.